Watts aren’t all equal. How to measure an Amplifier’s “Grunt”?
- Thread starter strummer
- Start date
Arkless Electronics
Trade: Amp design and repairs.
He was certainly vary much into marketing...
The level which is audible varies massively according to the order of the distortion and it's "spikyness". For very worst case 0.01% may be audible. If pure second harmonic then much more would be needed and small amounts would be reported by some as "better" than none!
S-Man
StrivingON
Can't argue with that!
Joe P
Memory Alpha incarnate | mod; Shatner number = 2
Jez,
Variably marketing? What's the potential for that?
OK, I'm done with bad puns...
Joe
Variably marketing? What's the potential for that?
OK, I'm done with bad puns...
Joe
Arkless Electronics
Trade: Amp design and repairs.
Bloody pedants...
Barrymagrec
pfm Member
I don`t know the precise connection between Manley Labs and Manley Van Nierkirk but I assume there is one.
Leevers Rich had dealings with Manley Van Nierkirk in 1969 / 70 - a very opinionated Dude, if I remember correctly, and keen on Leevers because by that time they were the only studio tape machine manufacturer still using valves.
Leevers Rich had dealings with Manley Van Nierkirk in 1969 / 70 - a very opinionated Dude, if I remember correctly, and keen on Leevers because by that time they were the only studio tape machine manufacturer still using valves.
ex brickie
Speakers matter
I wish I knew and understood the answer to the OP's question. My only direct experience that baffled me was several years ago when I owned AE1 (MkIII) standmounts which were difficult to drive. I used an Exposure pre-amp and 2 monoblocks and still had a very lifeless sound. I bought a secondhand Audiolab 8000S integrated amp for a different system but tried it out on the AE1s and they sang much more effortlessly. Go figure....
The problem really comes down to the requirements of marketing departments to have a single number that represents how good a product is, with bigger being better - watts is the equivalent of stating the horsepower of a car engine and thinking that that tells you all you need to know about a car.
You could indeed state the max current that can be supplied (as well) but this then gives you two numbers, and again this isn't the full story. It's the same as turning distortion into THD and thinking that two similar values would give you similar sounding amps. This attempt to simplify is pretty universal, and can be used to hide all sorts of nasties behind.
Personally I think if you stay within the capabilities of the amp you use then things should be rosy. Knowing what they are is all the numbers will hint at.
You could indeed state the max current that can be supplied (as well) but this then gives you two numbers, and again this isn't the full story. It's the same as turning distortion into THD and thinking that two similar values would give you similar sounding amps. This attempt to simplify is pretty universal, and can be used to hide all sorts of nasties behind.
Personally I think if you stay within the capabilities of the amp you use then things should be rosy. Knowing what they are is all the numbers will hint at.
S-Man
StrivingON
So if the low distortion tube buffer is providing low distortion, then what is it doing to the signal to improve it?
The Watt in this context is a product of voltage x amps so 50V x 1A = 50W & 1V x 50A also equals 50W. When you account for load impedance which usually varies with frequency, meaningful numbers that correlate to our subjective experience, go out of the window.
The Hi Fi industry does not have standards where every product type is measured in the same way & are very unlikely to do so. Take an amplifier with a stated output of say 100W rms into 8 Ohms with 0.1% THD distortion - many manufacturers will imply that these 2 measurements are effectively taken under the same conditions rather than the power adjusted to get the stated distortion or the distortion figure largely ignored to get the highest power figure. Does measuring distortion into an 8 Ohm resistive load really say much about the level of distortion likely to be obtained into a reactive load? It may do but I'm sceptical.
I smile when distortion further down the chain is quoted as 0.0001% when speakers have levels that are 1000s of times greater.
I contend that the industry could adopt more meaningful & consistent measurements but most marketing depts would block any such move very swiftly indeed.
The Hi Fi industry does not have standards where every product type is measured in the same way & are very unlikely to do so. Take an amplifier with a stated output of say 100W rms into 8 Ohms with 0.1% THD distortion - many manufacturers will imply that these 2 measurements are effectively taken under the same conditions rather than the power adjusted to get the stated distortion or the distortion figure largely ignored to get the highest power figure. Does measuring distortion into an 8 Ohm resistive load really say much about the level of distortion likely to be obtained into a reactive load? It may do but I'm sceptical.
I smile when distortion further down the chain is quoted as 0.0001% when speakers have levels that are 1000s of times greater.
I contend that the industry could adopt more meaningful & consistent measurements but most marketing depts would block any such move very swiftly indeed.
Jim Audiomisc
pfm Member
By the way, here are the Stingray's THD figures into an 8-, 4- and 2-Ohm load with the red blob being where I typically listen.
Likely below audibility, so lower THD wouldn't result in perceptively better sound.
Joe
How did you measure the power levels to determine your 'red disc' area is correct? Note the reason I ask is that real music often has peak/mean ratios *way* about 10dB. Thus playing at *power averaged* levels of half a Watt could still mean peaks well over 10 watts, for example. It isn't clear if your 'red disc' is time averaged, or how, etc.
You'd also need to factor in the real-world behaviour of your speakers not being simple resistive loads, the output transformers probably giving more nonlinearity at, say, 100Hz than at 1 kHz, etc, particularly into non-resistive loads. Also may be so for asymmetric waveforms - i.e. common in music but not a factor for sinewave tests.
I'm not saying you're wrong in what you prefer. Just exploring the possibility that the cause may be something which gets a 'bad label' like limiting distortion, etc.
Joe P
Memory Alpha incarnate | mod; Shatner number = 2
Jim,
No, I didn’t measure the amp’s power output, but I have an SPL meter that shows peak volume levels. My typical listening, while sitting on my couch, has peaks around 70db. The speakers are about 2 metres away.
My red disc was made in photoshop using the circular marquee tool and the paint bucket tool set to a pleasing shade of red and opacity at 15%.
Really, at the levels I typically listen, I could power my speakers with my headphone amp. Their sensitivity is about 100db for a watt at a metre.
I would wager that someone with small inefficient speakers powered by a big clean solid state amp has more distortion in practice because the speaker’s midrange driver is pretending to be a woofer.
Joe
No, I didn’t measure the amp’s power output, but I have an SPL meter that shows peak volume levels. My typical listening, while sitting on my couch, has peaks around 70db. The speakers are about 2 metres away.
My red disc was made in photoshop using the circular marquee tool and the paint bucket tool set to a pleasing shade of red and opacity at 15%.
Really, at the levels I typically listen, I could power my speakers with my headphone amp. Their sensitivity is about 100db for a watt at a metre.
I would wager that someone with small inefficient speakers powered by a big clean solid state amp has more distortion in practice because the speaker’s midrange driver is pretending to be a woofer.
Joe
Are you sure this is peak and not mean? If so the level is quieter than normal speech around that of background music in shops, restaurants, elevators,... Music at these sorts of levels is normally irritating to listen to due to missing high and low frequencies and a lack of clarity and detail. In more enlightened times one would press the loudness button to make things less bad. It will of course be relatively free of distortion due to this being buried well below background noise and possibly even your audibility threshold.
Snufkin
pfm Member
Taken mere moments ago while donning a Mr. Spock housecoat.
69.0 Max dbC
Joe
I think the 'Mr Spock housecoat' needs a thread of its own.
Arkless Electronics
Trade: Amp design and repairs.
That is illogical. Should be dBA also but that's well quiet.. like hg says a very quiet conversation in a quite room type quiet. Not also donning Spock ears by any chance?